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I'm looking for ideas and suggestions for putting together a small, non-contact thermal measuring device for finding hot spots on a circuit board. It needs to be small enough that I can toss it into my tool bag.

I currently use several techniques for finding hot spots on circuit boards. The most obvious technique is to simply slowly wave the back of your hand over the board - this finds significantly-hot areas easily. But this isn't necessarily a pin-point detector. It does have the advantages of being both free and always accessible, though.

I've also got a variety of temperature-measurement devices - these range from contact devices using a thermocouple or thermistor. In this case, though, I'm looking for non-contact temperature measurement. The equipment being debugged runs at high-voltage and stores significant amounts of energy.

My non-contact options are also several. I've got a couple of passive IR measuring devices: an older Fluke unit that uses a DMM for display, a couple of different passive IR units with built-in display, and a relatively-inexpensive FLIR thermal imager. The problem with all of these devices is size - they take up too much space in my tool bag.

Another technique that I use when locating hot devices on a PCB is to simply flood the area with Isopropyl Alcohol (IPA) and see what components evaporate the alcohol the quickest. Same problem with portability, though.

Ideally, this device would use something other than a meter for user feedback.

One of the most useful pieces of test equipment that I have is something called a "Leak Seeker" - this is essentially an auto-ranging and auto-nulling milli-ohmmeter that uses sound for user feedback. It is used to locate short circuits on circuit boards and has the compelling feature that you don't have to look at a display when using it - simply move the test probe to various nodes on the circuit board and listen for changes in tone pitch.

I want to do something similar with this device. It would always be indicating the change in temperature from some arbitrary reference temperature. One approach would be to simply store the current temperature when the device is powered ON and use a tone to indicate temperature changes relative to the reference temperature.

But that's about as far as I've gotten.

The initial stumbling block is a choice of sensor. I don't work with IR sensors and am not sure what I should be looking for when I begin my search for suitable devices.

What sensor can I use to make a small non-contact thermal measurement device?

update:

I got an email from someone pointing me to exactly what I'm looking for on Kickstarter. KickStarter DeltaK Temperature Indicator

Although this device is pretty much what I'm looking for, I'm still wanting to see what I might come up with myself.

My original question still stands: what particular sensor should I be looking for?

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  • \$\begingroup\$ Hmm... I found this rather novel approach... hackaday.com/2013/01/03/… \$\endgroup\$ – Trevor_G Mar 31 '17 at 17:06
  • \$\begingroup\$ The hackaday concept is novel and potentially interesting for another day. Saved in my bookmarks. Thanks! \$\endgroup\$ – Dwayne Reid Mar 31 '17 at 17:18
  • \$\begingroup\$ Ya I thought to so... I might just build one for fun \$\endgroup\$ – Trevor_G Mar 31 '17 at 17:23
  • \$\begingroup\$ Harbor Freight (and others) sells a pocket size remote IR thermometer with a laser pointer for only $19. \$\endgroup\$ – Barry Mar 31 '17 at 17:31
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    \$\begingroup\$ Yes it works but need low lux camera for best results and dark ambient. Convection heat can blur the image. Night vision uses photomultipliers. \$\endgroup\$ – Sunnyskyguy EE75 Mar 31 '17 at 18:21

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